Electric furnace.



J. w. BROWN.

ELECTRIC FURNACE. APPLIATION FILED m4. 8. 1912 v Patented Apr. 4,1916.

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ELECTRIC FURNACE. APPLICATION FILED JAN. 8, 1912.

Patented Apr. 4,1916.

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JOHN w. BROWN, 0E LAKEwoop, GHIOJASSIGNORITO NATIONAL CARBoN COMPANY, or LEVELAND, 01110, A CORPORATION OF NEW JERSEY.

ELECTRIC FURNACE.

Specification of Letters Patent;

' Patented Apr. 4, 1916.

Application filed January 8, 1912. Serial No. 6 70,07 1.

To all whom it may concern:

' Be it known that I JO -IN W. BROWN, a resident of Lakewood, in the county of Guyahoga, in the State of Ohio, have invented new and useful Improvements in Electric Furnaces, of. which the following is a clear and exact description.

facture of graphite and to the baking of cokes.

In the electric furnaces as usually constructed there is a large waste of heat due in part to the imperfect heat insulating me-- dium and to the large amount of heat contained in the treated charge when it leaves the heating zone. In order to continuously a wasted and one of the objects move the charge through the furnace it has heretofore been found necessary to cool it to. a temperature that would admit of its being conveyed out into the openair. The cooling has been done by forcing water through pipes in the lower part of the furnace. The heat absorbed by the water is all of my inventionvi's to save this heat. i i

' Another object of my invention. is to pre- I heat the charge 50 that it will notbe necessary to use so much electric energy.

Further objects will appear in the description-of my invention, particular reference being had to the drawings in which;

Figure 1 represents'the heating zone of a continuous furnace in which the charge is preheated by the combustion of part of the charge itself. Fig. 2 is another type of continous furnace in which the charge is preheated by inert gases passed therethrough. Fig. 3 is a detail of the form of carbon brick used in the furnace of Fig. 2. Fig. 4 is a sectional elevation of a type of furnace in which the charge is preheated by gases passing u ward through the charge and-also upwar through the walls of the furnace. Fig. 5 is another modification in which the charge is preheated by burning hot gases in the upper region of the furnace. The-figure isa section on AA of Fig. 6. Fig; 6 is a section on BB of Fig. 5. Fig. 7 is another modification in which the charge": is preheated by the combustion of both the charge itself and the hot gases.

This figure is a sectionon D,D of Fig. 8.

Fig.8 is a section on CC of Fig. 7.

Referring to Fig. -1 of the drawings. 1'

represents the outer' walls of the heating zone of the furnace made 0 some heat in-. sulating materlal well known in the art. 2

is the upper carbon electrode supporting a funnel shaped part 3. 4: is the lower electrode supportingthe'carbon electrode end 5. The electrode'ends 3 and 5 arepreferably screwed into the members 2 and 4. .The

electrical terminals are represented by- 6.

This furnace is adapted for using either direct or alternating current. 7 represents air pipes for conveying air under pressure to theupper part of the charge.

Granular coke is fed into the upper part of the furnace and removed from the lower part by screw conveyers. Since Fig. 1

illustrates only the heating zone of the furnace these conveyers are not illustrated. The granular charge will pass into the funnel shaped electrode 3 and out therefrom in the shape of a cone as clearly shown in the drawing.

The-current enters the two upper connections 6 and passing through the carbon electrodes 2 and 3 till it comes to the end of the electrode, then. it enters the granular charge and passes therethrough, to the lower electnode end 5, electrode 4 and lowerconnections 6. It will be understood that the two upper .connections 6 are connected to Y one bus bar and the two lower connections 6 are connected tothe other bus bar.

The granular charge'emerges from the electrode end 3 in the shape of a frustum of a cone and the upper'end of the cone c'an' be made very restricted incross section. so

the remainder is raised-to a high temperature. The amount of air in the pipes 7 can be regulated so that the operator can control the amount of the charge that is to burn. This preheating will amount to a great saving as the charge can be heated to ever, theheat of combustion is not suflic'ient' to graphitize the carbon. The. electric j current is employed to raise the temperature.- to the graphitizing point; It will-thusbe seenthatmy furnace can be operated at re-- 'duced expense.

; 1 The carbon charge always contains some 1 ing region these will volatilize and will pass I out into" the open-spaces 8 where they will. condense on the cooler -walls.'- .The coin densed material can be removed by pulling ash and volatile matter. In the electricheatout theblock 9 This is an important mat ter. If. no condensing chamber were provided the volatile matter would pass .up

through the, down-coming charge,-and would condense thereon. It will thus be seen' that.

the ash material would steadily increase if the condenser'were not used, preventing the continuous operation of the furnace.

In Fig. 2 the outer'walls l0 are made as usual of some heat insulating material that is a nonconductor-of electricity; The Walls are lined with a carbon. section 11 in the J shape of a frustum of a cone, a built-up sec-:

I "tion 112 made of corrugated: carbon blocks j shownin detail in Fig. 3,-and an insulating section. 13 in the shaped an inverted frustu'm of a cone. Thelower' electrode 14 is placed beneath and in contact with the member l'l'. The upperelectrode lt is.

l placed .on topof the memberl3. With the construction thus disclosed the current will flow from the upper'electrode 14f through the upperpart of the charge until the, builtup section 12 is reached? Here the greater part of theicu r rent willpassdown through." the constricted portion of the charge which is surrounded by the section12, and a small part ofit will flow through the section 12.

When the section 11 is reached the current again .will divide, most of it flowing through the carbon section 11 directly to the lower -'-electrode 14:. A small part of the current,

I 5 I heatingthe constricted portion of the charge. 5

however, will flow throughthelower part of the charge to the lower electrode,- The corrugated surface on the sections 1 2 increases the resistance to suchan extent-that onlyasmall part of the currentpasses therethrough. However,-the carbon blocks will be heated by this c'urrentand will aid in It will thus be seen that 'the charge. surrounded by the built-up section 12 can be quickly heated to a very high temperature. The charge is fed into the furnace by the screw conveyer 17 and removed therefrom an inert gas into the bottom of the furnace and withdraws it from the top. The gas absorbs the heat from the heated charge in the lower part ofthe furnace and cools it so. that it can be removedinto the air by.

y the screw conveyer 18. The fan 19 forces the conveyer. The hot .gas in passing through he Upper part of the furnace de- In practice: the furnace would be'20 or 30 feet high and the space above and below the heating zone-would begreat enough for the :gasto'absorb the heat from the lower-part of t he furnace and deliver substantially all of it up to-the upper part so that it would. e 'le'r ge therefrom in a practically cool state.

The valve 20 is for regulating the supply ofgas. 1 -In Flg. 41 two sets of upper electrodes 21 are -shown, each being similar to the one.-

shown'in Fig. 1; Only one lowerelectrode 22 is used. The three terminals can be com nected to a polyphas'e circuit or ifa single phase circuit is used the two upper elec:

trodes would be connected to the same terminal. The outer .wall 23 .is lined with carbon material 24 to resist the high heat which is necessary'to graphitize. the charge.

The condensingchamber is also lined with {carbon 25. Thespace 26 is filled with the granularmaterial to act as a heat. insulating medium. The funnel shaped part2? can be supported at varlous places, but such is not shown as such details are in the province of the mechanic and need not be shown. 28 p and 29 are conveyers for feeding and removing the charge.

In this figure gas is. circulated through the charge itself as in Fig. -2,'and also through the walls 23. In both the gas absorbs heat in the lower part blocks 31. p 2 p Fig. 5 shows in addition to the preheating system o'f fFig. 4: a heating zone dueto the combustion'of the gases. For this purpose air is blown inthrough pipes 2 by fan '33. On account of the combustion of the gas the pipes 33 open into the Hole 43. The burnt gas. ascends through the pipes 33 and does not go through the charge itself. The features of this furnace that are similar to those of Fig. t will not be further described. v v

Fig. 7 differs fromFig. 5 in' the provi-1 sion for the combustion of the gas. The air is blown directly into the charge through pipes 3eitas in Fig. 2. The gases well as part of the charge isthereby con-'- sumed. The gaseousproducts of combus-. tion pass out into the flue 34. Features similar to those of Fig. 4 havenot been deof the furnace, and gives it out to. .the 1 charge in the upper part. The fans 30' are controlled. This also enables me to use any of the preheating schemes as desired.

I do not limit my invention to the use of gases as a preheating medium when circulated through the furnace walls. Water or any other liquid such as molten alloys could also be used. By closing the appropriate valves 20 the fans or pumps -.could' circulate the liquid;

Having described my invention, what I claim is:

1. In an electric furnace for treating granular material, means for admitting an electric current to heat the material, a chamber for the untreated material, a second chamber for the treated material, means for forcing a combustible gas through the' material in the second mentioned chamber whereby heat is absorbed therefrom, and admitting it to the first mentioned chamber, and means for forcingair into the first chamber to burn the heated combustible gases so'as to preheat-the charge.

2. In an electric furnace, electrodes for 'heatmg the charge, means for forcing a combustible gas through the'treated charge to absorb the heat therefrom and means for forcing air into the furnace to burn the heated gas forced in by said first mentioned means.

-3. In an electric furnace, electrodes for heat ng the charge, means for forcing a combustible gas through the treated charge to cool the same and means for delivering air into the upper part of the furnace to cause the combustion of the charge and the combustible gas wherebyit is preheated.

. 4." In anelectric furnace, an upper Q1801 trode, a lower electrode, a chamber above the, first mentioned electrode, achamber below the second mentioned electrode, a conveyer for feeding the charge into the upper the first mentioned electrode, a chamber below the second mentioned electrode, means for delivering a combustible gas to the lower chamber, means for delivering airto the upper chamber whereby the treated charge in the lower chamber is cooled and the gas and part of the charge is burned m the upper chamber, and means whereby the treated charge-may be removed from the lower chamber.

.6; In .an electrical furnace, inclosing walls, an upper chamber therein for the untreated-material, a lower chamber for the treated material, a hollow upper electrode said lower chamber and a lower electrode in the lower chamber.

.7. In an electric furnace, inclosing walls,

an upper chamber therein having an opening in the bottom, a vertically arranged hollow electrode having a hopper beneath said opening, a chamber beneath said electrode and a second electrode therein.

' In'testimony whereof I have hereunto signed my name. v

' JOHN W. BROWN.

Witnesses I F, D. LAWRENCE, A. H. AVERY.

adapted to permit the passage of material therethrough from said upper chamber to 

